Unexpected Rock in NSW Civil Works: Contract Review for Variation and Delay Claims

John Merlo
16 hours ago
11 min read

Key Takeaways

Notify immediately: A valid claim can fail if notice is late, incomplete or sent to the wrong person.
Preserve the condition: Photograph and survey the affected area, invite the head contractor to inspect it and record the impact before changing the excavation method.
Check the risk allocation: The subcontract, tender assumptions and identified geotechnical baseline will shape whether the unexpected condition supports a variation or delay claim.
Separate entitlement from payment: The contract governs the underlying claim, while the NSW security of payment regime may provide a separate process for claiming and adjudicating payment.
Record the impact daily: Maintain contemporaneous records of labour, plant, standby time, changed methodology, disposal costs and program consequences.

Your 50-tonne excavator has struck solid sandstone where the principal’s geotechnical report indicated soft clay. Trenching has stopped, but labour and plant costs continue to accumulate. Within an hour, the head contractor rejects your variation request, relies on the subcontract’s site-conditions clause and insists that the pipeline works remain on program.

When unexpected ground stops excavation, the cost can rise by the hour. The first 48 hours are critical: you need to preserve the physical condition, comply with the subcontract’s notice requirements, document the time and cost consequences and obtain clear directions about how the work should proceed.

This article explains what NSW pipeline and civil subcontractors should do after encountering unexpected rock, contamination, groundwater or underground obstructions, including when to obtain early dispute advice. It also examines how to protect variation and extension-of-time claims, define the geotechnical baseline before signing a subcontract and pursue payment when a claim is rejected.

What to Do in the First 48 Hours

With labour and plant standing by, your immediate priority is to preserve the condition, check the subcontract and serve the required notices. Use the following checklist before the relevant notice period expires.

Immediate response checklist

Make the area safe and avoid disturbing the condition unnecessarily.
Check the latent-condition, variation, delay and extension-of-time clauses.
Identify the required recipient, delivery method and notice deadline.
Send a protective written notice immediately, even if the full impact is not yet known.
Invite the head contractor’s authorised representative to inspect the condition.
Photograph, video and survey the affected area against identifiable site references.
Record labour, plant, standby time and changed-method costs from the outset.
Request a written direction before adopting a different excavation or construction method.
Update the program and estimate the likely time impact.
Continue to provide updated particulars as the consequences become clearer.

Serve the Required Notices

Check the subcontract immediately. A notice will commonly need to identify the unexpected condition, when and where it was encountered, how it affects the work and the likely consequences for time and cost. It must also be sent to the correct recipient, using the method required by the subcontract, within the applicable notice period.

Do not wait until the full cost or program impact is known. Send an initial protective notice and state that further particulars will follow as the condition is investigated and quantified. Prompt notice gives the head contractor an opportunity to inspect the condition, issue directions and consider an alternative methodology. It also reduces the scope for a later argument that the claim was notified too late or that the head contractor was denied an opportunity to mitigate the impact.

A protective notice may use the following structure:

Subject: Notice of latent condition, delay and potential variation — [project and location]
We give notice that at approximately [time] on [date], the subcontract works encountered [describe the condition] at [precise location]. The condition differs from [identify the relevant tender, geotechnical or site information, if applicable].
The condition has affected, or may affect, [identify the activity], with potential consequences for time, cost, labour, plant and methodology. We invite your authorised representative to inspect the condition before it is disturbed and request a written direction regarding how the work is to proceed.
We are continuing to investigate and quantify the impact and will provide further particulars. This notice is given without waiver of, and with an express reservation of, our contractual and statutory rights.

The notice must be adapted to the subcontract’s wording, required recipient, delivery method and deadline. A site diary entry or informal discussion may be useful evidence, but it should not be treated as a substitute for any formal notice required by the contract.

Contract Entitlement and Payment Rights Are Different Issues

The subcontract governs the parties’ underlying arguments about responsibility for the unexpected condition. The NSW security of payment regime may provide a separate process for claiming and adjudicating payment, and timely security of payment advice may be required because statutory deadlines can be short.

Section 34 of the Building and Construction Industry Security of Payment Act 1999 (NSW) (SOP Act) gives the Act effect despite contractual provisions to the contrary and renders void provisions that exclude, modify or restrict the operation of the Act, or that may reasonably be construed as an attempt to deter a person from taking action under the Act. A subcontract therefore cannot remove or restrict statutory rights where the Act applies. However, access to the statutory process does not remove the need to establish and document the underlying claim or to consider the Act’s application and exclusions, including the exclusions in s 7 and the provisions concerning exempt residential construction contracts in ss 4 and 11.

Can an Unfair Site-Risk Clause Be Challenged?

Federal unfair contract terms legislation may be relevant where a standard-form subcontract imposes a substantial and one-sided allocation of subsurface risk. Under the Competition and Consumer Act 2010 (Cth), including Schedule 2—the Australian Consumer Law—a term in a consumer contract or small business contract may be unfair if it creates a significant imbalance in the parties' rights and obligations, is not reasonably necessary to protect the legitimate interests of the party advantaged by the term, and would cause detriment (whether financial or otherwise) if it were applied or relied on.

The assessment may include whether the subcontractor had a genuine opportunity to negotiate the clause, whether the risk could reasonably be priced and whether the subcontract identifies information on which the subcontractor was entitled to rely. The particular wording and contracting process will be critical.

Do not assume that a broad site-risk clause automatically ends the enquiry. Equally, do not proceed as though the clause has no effect. Serve the required notices, preserve evidence of the condition and obtain commercial law advice about the specific risk allocation before accepting the rejection of a claim.

Strict Time-Bars for Delay Claims

Unexpected ground is only one source of delay. The same notice machinery may apply to wet weather, restricted access, late drawings, authority inspections and other events affecting the program. A time-bar may extinguish an entitlement to an extension of time or additional payment if written notice is not served within the stipulated period. The outcome depends on the precise wording of the subcontract and whether its procedural requirements were satisfied. Early construction law advice can help identify the applicable clause, deadline and required form of notice before an entitlement is lost.

Connect Site Reporting to Contract Deadlines

Standard-form and bespoke subcontracts may prescribe very different notice periods. Some agreements allow several weeks, while others require notice within 24 or 48 hours.

Configure digital site diaries and supervisor reporting systems to alert the contract manager as soon as a potentially claimable delay is recorded.

The escalation process should identify:

the event and when it began;
the affected activity;
the relevant subcontract clause;
the contractual notice deadline;
the required recipient and method of service;
the immediate effect on labour, plant and access; and
the likely program consequences.

A daily site report may support the claim, but it may not satisfy a separate requirement to serve a formal notice. Supervisors should therefore know which site events must be escalated and who is responsible for issuing the contractual notice.

Contract Review Before Signing: Defining the Geotechnical Baseline

The strongest opportunity to manage subsurface risk usually arises before the subcontract is signed. The subcontract particulars should identify the information used to price and plan the work, rather than leaving the parties to argue later about what the subcontractor should have anticipated.

Before signing, check that the subcontract:

lists each geotechnical report, borehole log, contamination report, services search and tender addendum by date and revision;
identifies the trench alignments, depths and work areas to which the information applies;
states whether the subcontractor is entitled to rely on that information;
distinguishes isolated hard material manageable by ordinary excavation from conditions requiring different plant, methods, disposal pathways or approvals;
explains how rock, contamination, groundwater and underground obstructions will be measured and valued; and
avoids inconsistent wording that transfers all subsurface risk despite the stated geotechnical baseline.

A broad warranty that the subcontractor has independently satisfied itself about all ground conditions can create a substantial obstacle to a later claim. By contrast, identifying specific reports as “Reliance Information” can establish a clearer baseline against which the encountered condition can be assessed.

This drafting should be reviewed before execution, when the parties still have an opportunity to clarify, negotiate and price the risk.

When the Head Contractor Contributed to the Delay

If the head contractor caused or contributed to the relevant delay—for example, by failing to provide access or issuing revised drawings late—the prevention principle may become relevant. In simple terms, a party may face difficulty insisting on a contractual deadline where its own conduct prevented the other party from meeting it.

The application of the principle is fact-sensitive and should not be treated as a substitute for timely notice. Preserve the records needed to establish what occurred, including access records, drawing registers, requests for information, directions, correspondence and evidence showing when the missing input was requested and supplied.

If a notice period has already been missed, obtain advice promptly about the contract wording, the cause of the delay and whether the head contractor’s conduct affects its ability to rely on the time-bar.

Payment Rights: Three Clauses to Check

Preserving the contractual claim is the first task. The next is converting that claim into payment. A head contractor may reject the variation, rely on a pay-when-paid provision or point to a lengthy payment term in the subcontract. Where the SOP Act applies, and subject to any statutory exclusions, the statutory regime may override or render ineffective those contractual provisions.

1. Pay-when-paid provisions

Section 12 of the SOP Act provides that a pay-when-paid provision has no effect in relation to payment for construction work carried out or undertaken to be carried out, or related goods and services supplied or undertaken to be supplied, under a construction contract. Accordingly, where the Act applies, a head contractor cannot make its liability to pay a subcontractor, or the due date for payment, contingent or dependent on first receiving payment from the principal or on the operation of another contract. The scope of the protection still depends on whether the relevant work falls within the Act, including any applicable exclusions.

2. Long payment periods

Section 11(1B) of the SOP Act generally provides that, other than under an exempt residential construction contract, a progress payment to a subcontractor becomes due and payable no later than 20 business days after a payment claim is made, subject to any earlier payment date provided by the contract.

For a progress payment to a subcontractor under a construction contract other than an exempt residential construction contract, a contractual term requiring payment after 45 or 60 days cannot extend the statutory period in s 11(1B) of the SOP Act. Subcontractors should retain evidence showing when and how the payment claim was served.

3. Clauses restricting statutory claims

Section 34 of the SOP Act prevents parties from contracting out of, modifying or restricting the operation of the SOP Act, and also renders void provisions that may reasonably be construed as an attempt to deter a person from taking action under it. A term that purports to remove or restrict access to the statutory payment process may therefore have no effect.

In The Minister for Commerce (Formerly Public Works and Services) v Contrax Plumbing (NSW) Pty Ltd & Ors [2005] NSWCA 142, the NSW Court of Appeal considered whether specific contractual provisions affecting progress payment claims were susceptible to invalidity under s 34 of the Building and Construction Industry Security of Payment Act 1999 (NSW). The Court did not finally determine that those provisions were void under s 34. Hodgson JA considered that the argument that s 34 invalidated aspects of the relevant payment regime was “strongly arguable”, but that observation was not necessary to the outcome. Bryson JA did not join those observations, and Brownie AJA declined to express a view on the substantive s 34 issue.

NSW Government guidance on security of payment also confirms that a contractor’s entitlement to progress payments cannot be excluded merely by a contractual term stating that the contractor cannot claim them.

If payment is withheld

Take the following steps immediately:

Confirm that the document was intended to operate as a payment claim.
Identify when, how and on whom it was served.
Preserve proof of service.
Record when the payment schedule and payment were due.
Compare the scheduled amount with the amount claimed.
Identify the contractual and factual reasons given for non-payment.
Obtain advice about adjudication or debt-recovery deadlines before they expire. Depending on the payment documents and dispute history, court proceedings may also need to be considered.

Do not allow extended commercial negotiations to distract from applicable statutory deadlines. Any dispute strategy should preserve those deadlines while negotiations continue.

Conclusion

Unexpected ground conditions become expensive quickly, but the physical condition is only one part of the dispute. You must also preserve the evidence, comply with the subcontract’s notice requirements, quantify the impact and observe the relevant payment-claim timetable.

Before starting excavation, ensure that the subcontract identifies the geotechnical information forming the agreed baseline. If rock, contamination, groundwater or an underground obstruction is encountered, notify the head contractor immediately, document the condition thoroughly and obtain written directions before changing the work wherever practicable.

If a variation has already been rejected, compile the subcontract, tender information, geotechnical reports, notices, photographs, site diaries, directions, programs and cost records for urgent review.

Encountered unexpected ground or had a variation rejected?

Before the condition is disturbed or the next contractual deadline expires, Merlo Law can review the site-risk allocation, notice position and available payment pathway, then help you identify the next time-critical step.

Contact our team to request a consultation for an initial subcontract and claim review.

FAQs

What should I do immediately after encountering unexpected rock?

Make the area safe, avoid disturbing the condition unnecessarily and check the subcontract’s latent-condition, variation and delay clauses. Serve a protective written notice, invite the head contractor’s authorised representative to inspect the condition and begin recording the time and cost consequences immediately. Do not wait until the full impact is known before giving notice. State that the effect is still being investigated and that further particulars will follow.

Can a head contractor reject my claim because the subcontract says I assume all site risks?

The clause may create a substantial obstacle, but its wording, the incorporated geotechnical information, the tender assumptions and the contracting process all matter. A broad risk-transfer clause should be assessed alongside any reports or other documents identified as information on which the subcontractor was entitled to rely. Serve the required notices regardless, preserve evidence of the condition and have the specific risk allocation reviewed before accepting the rejection.

What happens if I miss a 24-hour notice period?

A clearly drafted time-bar may extinguish an entitlement to an extension of time or additional payment if the required notice is not served within the stipulated period. A site diary entry or informal discussion may not satisfy a separate requirement for formal notice.

The precise wording and surrounding circumstances remain important. If the deadline has already been missed, preserve all relevant records and obtain advice promptly about the available contractual arguments, including whether the head contractor’s conduct contributed to the delay or affected compliance.

Is a 60-day payment term enforceable in an NSW construction subcontract?

Where the SOP Act applies, and the contract is not an exempt residential construction contract, s 11(1B) generally provides that a progress payment to a subcontractor becomes due and payable no later than 20 business days after a payment claim is made. The contract may provide for an earlier payment date, but a longer subcontract payment period cannot extend the statutory period.

Keep evidence of when and how the payment claim was served and calculate the applicable deadlines carefully.

Can the head contractor withhold payment until it is paid by the principal?

Where the SOP Act applies, s 12 provides that a pay-when-paid provision has no effect in relation to payment for construction work or related goods and services.

This guide is for informational purposes only and does not constitute legal advice. For advice tailored to your specific circumstances, please contact Merlo Law